Ecology, Environment and Conservation Paper

SUITABILITY FORMULATION AND PREDICTION OF SEAWEED (GRACILARIA VERRUCOSA) PRODUCTIVITY IN A POND AREA

Agus Dharmawan, Nuddin Harahab, Muhammad Musa and Soemarno

Abstract

Gracilaria verrucosa is one of red algae that can be cultivated in the pond area. A pond is an artificial ecosystem so that all abiotic components that work can be controlled to get the expected productivity. This study aims to formulate land suitability for seaweed Gracilaria verrucosa cultivation based on abiotic factors that have significant influence by considering the interrelationship and effect of each factor on productivity. The research sample was 161 ponds of total 670 ponds, with the independent variable is abiotic components including pH, surface current, brightness, turbidity, depth, dissolved oxygen, N fertilization, salinity, pond substrate, water temperature, and the dependent variable is wet weight seaweed harvest per unit area. The measurement data for abiotic components are classified in three categories according to the range of suitability for Gracilaria verrucosa growth, that is category 3 (suitable), category 2 (less suitable), and category 1 (not suitable). Multiple linear regression analysis is performed to determine the contibution value (weight) of each abiotic component on seaweed productivity. Cluster analysis to classify suitability and productivity scores, and Mann Withney test for comparison between groups were used. The result of this study is the Land Suitability Formula for Gracilaria verrucosa. The equation of relationship between suitability score (x) with seaweed productivity (y) in the dry season is y = 1.7081x + 0.7181, while in the rainy season is y = 1.7247x + 1.101. The formulation test shows that the relationship between the suitability score and seaweed productivity can be grouped into three based on the similarity of their numerical characters with the limitation of the suitability score for the dry season <3.359 = not suitable, 3.359 – 4.240 = less suitable, > 4.240 = suitable. For the rainy season is <3.549 = not suitable, 3.649 – 4.196 = less suitable, > 4.196 = suitable. The results of predicted productivity in the dry season <6,454 ounces/m2 = not suitable, 6.454 – 7.958 ounces/ m2 = less suitable, > 7.958 ounces/m2 = suitable, while in the rainy season <7.394 ounces/m2 = not suitable, 7.394 – 8.338 ounces/m2 = less suitable, > 8.338 ounces/m2 = suitable. Statistical tests show that Gracilaria verrucosa productivity of the three groups for both dry and rainy seasons is significantly different.